The iPad's USB charging caveat

Among all the new excitement from Saturday's iPad launch, new confusions over the device's ability to charge over USB have started to appear. Customers are reporting that their newly purchased iPads aren't charging over USB on both Windows and OS X based computers.

The iPad specifications page clearly state the ability to charge with USB (with no mention of OS requirements) but Apple have additionally provided a support document disclosing that "some USB 2.0 ports and accessories do not provide enough power to charge iPad."

Providing some further clarification to Macworld, Apple asserts that USB charging is supported but that it varies according to the state of the iPad and the power output of the USB hub:

  • For the fastest charging, use the iPad’s included 10-Watt USB power adapter. This will fully charge the iPad in a few hours, even if you’re using the iPad at the same time.
  • When connected to a high-power USB port—such as the ones on recent Macs and the iPhone Power Adapter—the iPad will charge, even during use, but more slowly. (We haven’t yet determined how much more slowly.) Some third-party powered USB hubs provide higher-power USB ports, but many don’t; similarly, the USB ports on most Windows PCs don’t provide this additional power.
  • When connected to lower-power USB ports—those on older Macs, most Windows PCs, and most USB hubs (powered or unpowered)—the iPad’s battery is not charged while the iPad is awake, but is charged (again, slowly) when the iPad is asleep. What’s confusing here is that the message "Not charging" appears in the menu bar when the iPad is awake, which might lead you to assume that the offending USB port can never charge your iPad. But rest assured, Apple says: once you put the iPad to sleep, the battery will indeed charge. (If you could see the screen while the iPad was asleep, it might even display the charging icon. It’s the modern-day “Does the refrigerator light stay on when I close the door?” mystery.)

Further analysis from Apple's statements indicate that the iPad can only be charged off of USB connections that provide near 1 amp of current. The majority of USB ports on most older Macs and PCs only provide 500 mA and thus can't be used to charge the device. 

The USB 2.0 specification provides 500 mA of current to high-powered buses and 100 mA for low-powered buses. But in April 2009, the specification gained a new "Battery Charging Specification" which provided additional current to high power devices and it seems that Apple has started to incorporate it in their newer Macs.

For example, a 2009 Unibody Macbook Pro provides 500 mA extra current when connected to an iPad:

Apple's support document states that the iPhone power adapter can charge the iPad, which doesn't come as a surprise now since it's rated at 1 amp. The included 10-watt power adapter for the iPad is supposedly rated at 2 amps. Macworld's additional tests seem to show that the iPad can keep its charge when connected to a low-powered port, indicating that it at least would not die on you when syncing with iTunes. 

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I find it pretty comedic that this was not forefront news when the iPad was announced. I hope their policy accepts returns! The darn thing is an over-sized iPhone/iPod touch! If people were aware of this, I'm sure sales would be half what they are.

Why I stick to devices that share the same charger. Hell, my phone, MP3 player, video camera, camera, and several other devices use the same damn cord. Apple doesnt do this and you end up paying for it.

It's interesting to see this. I always thought that the USB charging was flaky at best. My daughter has one of the older iPod Shuffles and that doesn't charge on my wife's laptop very well, yet it does on mine. I may have to see if there's a wall charger for her.

Couldn't they have avoided this by releasing a dual dongled cable? See them with all USB 3G modems (In Europe anyway).

thommcg said,
Couldn't they have avoided this by releasing a dual dongled cable? See them with all USB 3G modems (In Europe anyway).

I doubt that would go down well with Apple's style department.

thommcg said,
Couldn't they have avoided this by releasing a dual dongled cable? See them with all USB 3G modems (In Europe anyway).

I hardly see any in Europe, most are just single dongles now

so let me get this straight... some usb ports cant charge the ipad as fast (if at all) as people would like. Apple included a wall charger with the ipad. i dont see a problem here.

Whats with all these people saying USB HDD's require more power?

IF it is a full sized HDD ok. But laptop drives? I have used a good 10-15 models of laptop drives (build your own and factory made) and NEVER needed more than 1 USB port on any computer I have plugged them into.

necrosis said,
Whats with all these people saying USB HDD's require more power?

IF it is a full sized HDD ok. But laptop drives? I have used a good 10-15 models of laptop drives (build your own and factory made) and NEVER needed more than 1 USB port on any computer I have plugged them into.

And I have had a couple that did (an external slimline DVD burner did as well). Just because you haven't seen any doesn't mean they don't exist.

necrosis said,
Whats with all these people saying USB HDD's require more power?

IF it is a full sized HDD ok. But laptop drives? I have used a good 10-15 models of laptop drives (build your own and factory made) and NEVER needed more than 1 USB port on any computer I have plugged them into.

No external hard drives (2.5" or 3.5") work off the USB port on my Dell Inspiron 600m, even with a double-dongle. There's insufficient power. I need to connect a powered USB hub to make them work.

Yeah, this is a really serious problem on Apple's part. If they knew it would need a wall adapter to charge, they should have included one!

Oh, wait.

Can I ask, why do a high percentage of Neowins posters have low IQ that they can't respond to an article without misunderstanding it?

evo_spook said,
Can I ask, why do a high percentage of Neowins posters have low IQ that they can't respond to an article without misunderstanding it?

I think everybody understand the problem but is funniest to goof about this trouble instead of reclaim (again) about a misleading feature.

naap51stang said,
Which is why you let the early adopters sort out the bugs....NEVER buy 1.0 of ANYTHING.

*stares blankly* but it's not a bug... Apple says to charge it in the wall.. who wants to charge by USB anyway.. it's too difficult to find USB ports these days

Edited by crashguy, Apr 4 2010, 10:06pm :

Just wait for some 2USB <=> iPad adaptater from some manufacturer and it will be OK (in the same way some HDD can use 2 USB ports to drain enough power).

So will the new Gigabyte motherboards with 3x USB power (1500mA) like the P55A-UD4P that i got be able to charge the iPad?

Considering the size of it I wouldn't have expected to be able to charge it over USB either. There's only so much power a USB port can produce after all.

protocol7 said,
Considering the size of it I wouldn't have expected to be able to charge it over USB either. There's only so much power a USB port can produce after all.

There'll be unofficial charging adaptors which integrate a power supply but still use the official cable (is my guess -- I'm betting that it'll graciously accept any power shoved into it without a fuss). So, it'll be a tiny USB cable with a cable coming out of it which connects to a power supply that connects to the PC male end of the existing one. Or you can probably make your own to supplement USB power. I'm also guessing that the USB port won't supply any power if it detects that the device has got enough, or will it? By the way, the Tapwave Zodiac (http://en.wikipedia.org/wiki/Tapwave_Zodiac - I have one) did *exactly this* to supplement the USB power, so it does work! The only problem is whether the device must report its power consumption.

Edited by Dessimat0r, Apr 4 2010, 3:25pm :

Dessimat0r said,

There'll be unofficial charging adaptors which integrate a power supply but still use the official cable (is my guess -- I'm betting that it'll graciously accept any power shoved into it without a fuss). So, it'll be a tiny USB cable with a cable coming out of it which connects to a power supply that connects to the PC male end of the existing one. Or you can probably make your own to supplement USB power. I'm also guessing that the USB port won't supply any power if it detects that the device has got enough, or will it? By the way, the Tapwave Zodiac (http://en.wikipedia.org/wiki/Tapwave_Zodiac - I have one) did *exactly this* to supplement the USB power, so it does work! The only problem is whether the device must report its power consumption.

Or there will be charging plugs that plug into the same USB port (like not just Moto's RAZR-based phones, including the W7xx, and RIM's BlackBerries, including the Curve/Tour/Bold/S1/S2). The Moto/RIM plug/charger is very elegant; the blades fold in/out so it fits into a minimal space when not in use while taking up the same amount of space [on a strip] when *in use* as a small coffeemaker or pencil sharpener, as opposed to it being a typical *wallwart* charger. I have one that I use with a W755.)

It takes a long ass time to charge when hooked up to the mac. But it is stupid quick when plugged into the wall. Kinda sucks, but I can deal with it. The battery on this thing does last long enough.

MillionVoltss said,
Anyone tried USB 3 ?

Indeed, USB3 should provide the required amount of power. For USB2 under the enhanced specs, 9W is just under the 10W that it should be capable of putting out. Additionally, 1.8A is just under the 2A required. However, this is from a dedicated port. A non-dedicated port can only put out 1.5A, so this will impact upon the charging speed.

From Wikipedia:

In Battery Charging Specification[35], new powering modes are added to the USB specification. A host or hub Charging Downstream Port can supply a maximum of 1.5 A when communicating at low-bandwidth or full-bandwidth, a maximum of 900 mA when communicating at high-bandwidth, and as much current as the connector will safely handle when no communication is taking place; USB 2.0 standard-A connectors are rated at 1500 mA by default. A Dedicated Charging Port can supply a maximum of 1.8 A of current at 5.25 V. A portable device can draw up to 1.8 A from a Dedicated Charging Port. The Dedicated Charging Port shorts the D+ and D- pins with a resistance of at most 200Ω. The short disables data transfer, but allows devices to detect the Dedicated Charging Port and allows very simple, high current chargers to be manufactured. The increased current (faster, 9W charging) will occur once both the host/hub and devices support the new charging specification.

About USB3:

The bus power spec has been increased so that a unit load is 150 mA (+50% over minimum using USB 2.0). An unconfigured device can still draw only one unit load, but a configured device can draw up to six unit loads (900 mA, an 80% increase over USB 2.0 at a registered maximum of 500 mA). Minimum device operating voltage is dropped from 4.4 V to 4 V.

Edited by Dessimat0r, Apr 4 2010, 2:22pm :

For those of you saying that the iPad of 2 or 3 years time will sort this out... the only thing that's going to change in 2 or 3 years is that your new computer might be able to send out the higher power charge, Apple wont change a thing.

Darran said,
For those of you saying that the iPad of 2 or 3 years time will sort this out... the only thing that's going to change in 2 or 3 years is that your new computer might be able to send out the higher power charge, Apple wont change a thing.

+1 This is not a problem with the iPad's hardware.

Elliott said,

+1 This is not a problem with the iPad's hardware.

Unless I'm misreading the Apple site, USB is the only way to charge it out of the box, and they're trying to draw way to much power over USB than most computers can handle. Seems like thats a hardware problem to me.

Typical Apple trying to push its accessories. Its a computer really, it should have a power supply.

Pc_Madness said,

Unless I'm misreading the Apple site, USB is the only way to charge it out of the box, and they're trying to draw way to much power over USB than most computers can handle. Seems like thats a hardware problem to me.

Typical Apple trying to push its accessories. Its a computer really, it should have a power supply.

The power adapter is included, so yes, you are misreading something.
http://www.apple.com/ipad/specs/

In the box
iPad
Dock Connector to USB Cable
10W USB Power Adapter
Documentation

What's the big deal. You can still charge the unit by simply plugging it in. Come on people this is just plain stupid. . .plug the da. .thing into a wall socket, hence, problem solved.

Am I the only one that thinks they should've put USB ports and a MagSafe socket on it instead of the dock connector?

PureLegend said,
Am I the only one that thinks they should've put USB ports and a MagSafe socket on it instead of the dock connector?

The dock connector is a must if it's using the iPhone OS. There are apps out there with dongles that attach to the dock connector (like the iTrip).

Edited by Elliott, Apr 4 2010, 1:25pm :

I don't see the big issue with losing USB actually. For keyboards it would be nice but I think they allow bluetooth ones anyway. As for other devices I think it would be an exercise in frustration given the way Apple has designed the OS is very closed and as such I doubt they want to give you access to mass storage which would rule out the majority of other devices I imagine you would want to plug into it anyway (cameras, usb sticks ect).

While it'd be nice it doesnt really fit Apples strategy.

Smigit said,
I doubt they want to give you access to mass storage which would rule out the majority of other devices I imagine you would want to plug into it anyway (cameras, usb sticks ect).

While its not integrated in the iPad, they do offer USB and SD dongles that allow for importing from a camera.

When connected to lower-power USB portsâ€"those on older Macs, most Windows PCs,

Well at least Apple remains unbiased and truthfull in their statements...

Most windows PC's come with low powered USB ports now....

HawkMan said,

Well at least Apple remains unbiased and truthfull in their statements...

Most windows PC's come with low powered USB ports now....

lower-power

A shame but not altogether surprising if I'd thought about it. No conspiracy here, just power-hungry devices!

Hmm...I also can't charge my netbook over USB, in my view its obvious that a device like this is going to need a higher spec'd power source to boost its batteries. At least if it can't charge it it appears to sustain its power level while connected.

To the comment about "windows PC's", is it not an acceptable way refer to a piece of computer hardware that isn't made by Apple, after all the use of windows vs other PC based operating systems post Microsoft at the top of the market share tables?

If you're looking for a less power hungry device, you'll find that in the Apple store in the iPod Touch/iPhone section

netutgamer said,
Hmm...I also can't charge my netbook over USB, in my view its obvious that a device like this is going to need a higher spec'd power source to boost its batteries. At least if it can't charge it it appears to sustain its power level while connected.

To the comment about "windows PC's", is it not an acceptable way refer to a piece of computer hardware that isn't made by Apple, after all the use of windows vs other PC based operating systems post Microsoft at the top of the market share tables?

If you're looking for a less power hungry device, you'll find that in the Apple store in the iPod Touch/iPhone section

Apple said that the iPad is able to charge via USB. No netbook claim the same.

day2die said,

Apple said that the iPad is able to charge via USB. No netbook claim the same.


And that claim is still valid. USB ports that implement the newer battery charging specs (like on newer Macs) can charge the iPad. It only needs 1A to at least charge slowly and can even charge off of 500mA as long as you don't turn it on and use it.

Edited by Elliott, Apr 4 2010, 3:25pm :

Elliott said,

And that claim is still valid. USB ports that implement the newer battery charging specs (like on newer Macs) can charge the iPad. It only needs 1A to at least charge slowly and can even charge off of 500mA as long as you don't turn it on and use it.
But they really should have footnoted that requirement, especially considering how new it is.

cybertimber2008 said,
But they really should have footnoted that requirement, especially considering how new it is.

It's not really new. Many 2.5" mobile hard drives also require 1A of power to operate. At least the iPad can still charge from 500mA.

day2die said,

Apple said that the iPad is able to charge via USB. No netbook claim the same.

And it can. Even in the low-power USB port scenario above, it charges. It doesn't run and charge at the same time, but it charges.

thealexweb said,
Apple discretely slagging of Windows PCs there, here's an idea Apple, you should have made a less power hungry device.
None of the linked Apple sites say that. Only the MacWorld site, claiming the info was based on their experience combined with info received from Apple.

And, for what it is worth, my Blackberry doesn't charge on USB ports on most PCs, but does on my wife's Apple. Another Apple conspiracy to make Microsoft look bad? I think not.

Edited by markjensen, Apr 4 2010, 12:31pm :

thealexweb said,
Apple discretely slagging of Windows PCs there, here's an idea Apple, you should have made a less power hungry device.

I've seen the same kind of thing with several HTC phones as well, so Apple isn't alone here.

roadwarrior said,

I've seen the same kind of thing with several HTC phones as well, so Apple isn't alone here.

Really? I've owned 6 HTC phones and never seen this issue. I mean they all use pretty much the same adapter and require the same power. Only exception is HTC shift.

markjensen said,
And, for what it is worth, my Blackberry doesn't charge on USB ports on most PCs, but does on my wife's Apple. Another Apple conspiracy to make Microsoft look bad? I think not.

You need to install the Blackberry USB driver to enable fast charging. The phone when plugged in requests the PC to up the amperage coming out of the USB port. The driver handles the request. It will charge without it, just very slowly.

Edited by WK80, Apr 4 2010, 1:58pm :

roadwarrior said,

I've seen the same kind of thing with several HTC phones as well, so Apple isn't alone here.

Which? I've only had two (Touch HD and HD2) and neither have charging problems on my PC. Having said that, I prefer to charge from the wall to prevent WMDC launching each time I connect the phone to the PC.

WK80 said,

You need to install the Blackberry USB driver to enable fast charging. The phone when plugged in requests the PC to up the amperage coming out of the USB port. The driver handles the request. It will charge without it, just very slowly.

Don't I know it!

When I plug in, it gives a "USB charging is not sufficient." message that takes up a good portion of the screen. But leaving it plugged overnight, it does slowly charge.

Much like the iPad, it seems. And I am just as (not) outraged over the iPad as I am over the Blackberry.

Fred 69 said,

Which? I've only had two (Touch HD and HD2) and neither have charging problems on my PC. Having said that, I prefer to charge from the wall to prevent WMDC launching each time I connect the phone to the PC.

Cingular 8125 and AT&T Tilt (both phones built by HTC). Both come with a 1A wall charger, and neither would charge from some of my older computers' USB ports when they were very low on battery unless I had the phone turned off. Only one of my computers (the newest one) would charge them from a completely dead battery off of the USB port, and the charger for my wife's Motorola RAZR (which had the same kind of USB charging port, but was only 500ma, like most USB ports) wouldn't charge them either.

markjensen said,
None of the linked Apple sites say that. Only the MacWorld site, claiming the info was based on their experience combined with info received from Apple.

And, for what it is worth, my Blackberry doesn't charge on USB ports on most PCs, but does on my wife's Apple. Another Apple conspiracy to make Microsoft look bad? I think not.

I charge my Blackberry every night from my laptop, actually it charging as I write this.

thealexweb said,
Apple discretely slagging of Windows PCs there, here's an idea Apple, you should have made a less power hungry device.

+1 Indeed.

Further analysis from Apple's statements indicate that the iPad can only be charged off of USB connections that provide near 1 amp of current. The majority of USB ports on most older Macs and PCs only provide 500 mA and thus can't be used to charge the device.

The USB 2.0 specification provides 500 mA of current to high-powered buses and 100 mA for low-powered buses.


Basically what they're saying is that the iPad does not support USB 2.0 spec ports for charging.

Edited by Ryster, Apr 4 2010, 4:40pm :

TCLN Ryster said,

Basically what they're saying is that the iPad does not support USB 2.0 spec ports for charging.

Did you just completely ignore some of the posts above that state that the USB specs were updated last year to allow for more power? Unfortunately, many computers already in service, and even some new ones, don't support this newer spec.

roadwarrior said,

Did you just completely ignore some of the posts above that state that the USB specs were updated last year to allow for more power? Unfortunately, many computers already in service, and even some new ones, don't support this newer spec.


I'm sorry, I missed the word Original out. Forgive me great one.

markjensen said,
None of the linked Apple sites say that. Only the MacWorld site, claiming the info was based on their experience combined with info received from Apple.

And, for what it is worth, my Blackberry doesn't charge on USB ports on most PCs, but does on my wife's Apple. Another Apple conspiracy to make Microsoft look bad? I think not.

Ya, same here. My Blackberry won't charge on my older PCs (even though it has USB2.0 ports). Only chargeable via USB on my newer PCs. I guess the supplied current on the USB2.0 ports are different between the older mainboards and newer ones.

roadwarrior said,

Cingular 8125 and AT&T Tilt (both phones built by HTC). Both come with a 1A wall charger, and neither would charge from some of my older computers' USB ports when they were very low on battery unless I had the phone turned off. Only one of my computers (the newest one) would charge them from a completely dead battery off of the USB port, and the charger for my wife's Motorola RAZR (which had the same kind of USB charging port, but was only 500ma, like most USB ports) wouldn't charge them either.

RAZR REQUIRES DRIVERS. UGH! Im sick of people not understanding this. No drivers = Windows dosent know WTF the device is so it shuts off power to the port. Windows does this with EVERY USB DEVICE.

RAZR has no removable memory so it can not act like a "USB flash drive" so windows will not send power unless you search the internet for the flashing tools the factory uses to flash the phone/transfer themes. That package has a Windows driver so it knows what the device is and will start sending power to the device.

Please DO NOT confuse "Windows does not know WTF it is so it wont send power" with "USB not sending enough power".

necrosis said,
RAZR REQUIRES DRIVERS. UGH! Im sick of people not understanding this. No drivers = Windows dosent know WTF the device is so it shuts off power to the port. Windows does this with EVERY USB DEVICE.

Learn to read. Nowhere in my post did I say I was trying to charge the RAZR from the USB port. I merely stated that the CHARGER for my wife's RAZR (meaning the wall charger, since you are clearly not able to understand this) wouldn't charge the HTC phones due to the current rating on it being too low. Both the HTC phones I had and the RAZR used standard 5V mini-USB connections for charging, but the HTC phones required 1A to charge, the RAZR only required half of that.

Also, the model of RAZR my wife had was a V3i (the iTunes model) which did have removeable memory.

Edited by roadwarrior, Apr 5 2010, 1:20pm :

necrosis said,
No drivers = Windows dosent know WTF the device is so it shuts off power to the port. Windows does this with EVERY USB DEVICE.

Couldn't edit my other post, but thought this was important enough to mention: you are full of **** on this. I have quite a few devices around here that can be powered from a USB port that Windows doesn't have the first clue about WTF they are. Where did you get this idea?

roadwarrior said,

Couldn't edit my other post, but thought this was important enough to mention: you are full of **** on this. I have quite a few devices around here that can be powered from a USB port that Windows doesn't have the first clue about WTF they are. Where did you get this idea?


This is purely anecdotal evidence, but my observations say that unrecognised devices DO get power, but not as much as when the driver is installed. The iPhone for instance charges if I plug it into my computer, but extremely slowly. Once I install iTunes (and therefore the iPod/iPhone drivers), it charges much more quickly. Another example is my Logitech G13. If I plug it into a new computer, it gets some power because the LCD turns on and says G13 in big letters on the screen. But it's not until I install the drivers that the backlight can be turned on with the backlight button on the device.

TCLN Ryster said,

This is purely anecdotal evidence, but my observations say that unrecognised devices DO get power, but not as much as when the driver is installed.

Even if this happens with some devices, Necrosis is still full of **** because he makes the claim that Windows shuts off the power to USB ports when it detects a device that it doesn't recognize.

I have never seen such a heated debate on charging batteries. Even so far as calling each other names. Use a wall charger... and get on with your lives.

Understandable, I wonder if the HP slate will have the same problem or even allow charging via usb.

I'd just use the wall charger at night, same as I do with my iPhone.

acnpt said,
Understandable, I wonder if the HP slate will have the same problem or even allow charging via usb.

I'd just use the wall charger at night, same as I do with my iPhone.

yeah. My thoughts exactly, although apple could have been more specific initially.
I can't think of anything larger than a cell phone I've ever seen charge over USB. Not that I wouldn't want to see more things charge over USB …

acnpt said,
Understandable, I wonder if the HP slate will have the same problem or even allow charging via usb.

I'd just use the wall charger at night, same as I do with my iPhone.


I agree, it goes without saying that usb doesn't charge as much over usb under some conditions. It's simply technically impossible. I sometimes charge my phone via my computer, but only in emergencies (no charger accessible), and even then, charge time is of course much slower.

Edited by Northgrove, Apr 4 2010, 7:10pm :

acnpt said,
Understandable, I wonder if the HP slate will have the same problem or even allow charging via usb.

I'd just use the wall charger at night, same as I do with my iPhone.

It probably won't support it at all. It is a standalone computer.

"similarly, the USB ports on most Windows PCs don’t provide this additional power."
Hahaha, that's just bloody stupid! As if software has anything to do with hardware.

mr.r9 said,
"similarly, the USB ports on most Windows PCs don’t provide this additional power."
Hahaha, that's just bloody stupid! As if software has anything to do with hardware.

They didn't mention anything about "Linux PCs"

mr.r9 said,
"similarly, the USB ports on most Windows PCs don’t provide this additional power."
Hahaha, that's just bloody stupid! As if software has anything to do with hardware.

That quote doesn't imply that it's the software's fault though.

mr.r9 said,
"similarly, the USB ports on most Windows PCs don’t provide this additional power."
Hahaha, that's just bloody stupid! As if software has anything to do with hardware.

I assume that like me, you hate Apple; but that statement is somewhat correct. Their newer computers all follow the newer 1A spec (which they enforce) whereas "Windows machines" depend on who builds them. I used to wonder why my Dell laptops had no problems running my external 7200rpm HDD with just one USB plug but my desktop couldn't until I learnt about this.

kInG aLeXo said,

They didn't mention anything about "Linux PCs"
Hold on... I'm still compiling the usb_pwnage_4kw option into the kernel, but I am missing the überleet library.

Fred 69 said,
Their newer computers all follow the newer 1A spec (which they enforce) whereas "Windows machines" depend on who builds them.

There is no such "spec". There are some little things called "standards". I guess it's very good for Apple to repeatedly violate them.
A unit load is defined as 100 mA in USB 2.0. A maximum of 5 unit loads (500 mA) can be drawn from a port in USB 2.0

Neowin didn't let me edit my comment...

In the second half of 2009 the "Battery Charging Specification" was released. And there's no "1A spec" in it. Just 900mA and 9W maximum. Specification that Apple deliberately violates.

The increased current (faster, 9W charging) will occur once both the host/hub and devices support the new charging specification.

Edited by RealFduch, Apr 4 2010, 1:21pm :

mr.r9 said,
"similarly, the USB ports on most Windows PCs don’t provide this additional power."
Hahaha, that's just bloody stupid! As if software has anything to do with hardware.

apart from the ports on my keyboard and usb hubs/switches without their own powersupply ive never encountered a usb port that does not supply power...

Leonick said,

apart from the ports on my keyboard and usb hubs/switches without their own powersupply ive never encountered a usb port that does not supply power...

The key word there is "additional". Yes, your USB ports provide power, as do most on anything other than a keyboard or other non-powered hub. What they don't likely do is provide more than 500ma of power. Read the other replies above for the CURRENT specs, which allow for more, and which the iPad needs.

RealFduch said,

Where does your link say anything about "1A spec" (=10W)?

Miss this part?:

A host or hub Charging Downstream Port can supply a maximum of 1.5 A when communicating at low-bandwidth or full-bandwidth, a maximum of 900 mA when communicating at high-bandwidth, and as much current as the connector will safely handle when no communication is taking place